The present invention relates to improved cleaning compositions comprising organic amines, particularly, monoethanolamine, tetramethylammonium hydroxide, fluoride containing salts, a corrosion inhibitor e.g. ascorbic acid, surfactant and water.
The present invention relates to a cleaning composition for semiconductor substrate surfaces used in the Back End of The Line (BEOL) production steps during the manufacture of semiconductor devices. In particular those semiconductor devices where copper is used as the conductor and interconnects with regard to a process known as double damascene. During BEOL manufacturing steps used in the production of the newest semiconductors and semiconductor microcircuits copper, (Cu) is used to produce the latest high-density devices. Surface etching of the various substrates is one step utilized to build the circuits during manufacturing of a semiconductor device. Following these etching processes the remaining photoresist, comprising an organic coating deposited on the substrate to be etched, is removed by wet or dry stripping methods, generally called ashing. Subsequently it is necessary to remove any residual organic and inorganic contamination remaining, commonly referred to as sidewall polymer (SWP). This SWP typically consists of post etch and post ash residues such as polymers, salts, metallic contamination and particles. It is desirable to develop an improved cleaning composition to remove the SWP without corroding, dissolving or increasing the resistance of the metal circuitry or chemically altering the exposed substrates on the wafer surface.
Amine solvents currently used to remove these residues corrode the copper substrates and cause degradation or failure of the intended device. It is therefore desirable to provide solutions containing corrosion inhibitors such that these compositions can be used to remove various types of residues from copper substrates and dielectrics without degrading or destroying the device.
U.S. Pat. No. 4,617,251 to Sizensky discloses a cleaning composition that is prepared with a select amine and an organic polar solvent. This composition is formed utilizing from about 2% to about 98% by weight of amine compound and about 98 to 2% of an organic polar solvent.
U.S. Pat. No. 4,770,713 to Ward discloses a cleaning composition comprising an alkylamine and an alkanolamine.
U.S. Pat. No. 5,419,779 to Ward discloses a process for removing an organic coating from a substrate by applying a composition consisting of about 62% by weight of monoethanolamine, about 19% by weight hydroxylamine, a corrosion inhibitor that includes gallic acid and gallic acid esters, and water.
U.S. Pat. No. 5,997,658 to Peters et al. discloses cleaning compositions comprising water, an alkanolamine and a corrosion inhibitor being one of, benzotriazole gallic acid and gallic acid esters.
U.S. Pat. No. 5,597,420 to Ward discloses a cleaning composition free of hydroxylamine compounds that consists essentially of monoethanolamine and water together with a corrosion inhibitor. The preferred inhibitor includes gallic acid and it""s esters.
European Patent No. 0647884A1 to Schwartzkopf et al, discloses photoresist strippers containing reducing agents to reduce metal corrosion. This patent teaches the use of ascorbic acid, gallic acid pyrogallol among others for the control of metal corrosion in alkali containing components.
U.S. Pat. No. 5,143,648 to Satoh et al., discloses novel ascorbic acid derivatives as antioxidants.
U.S. Pat. No. 5,972,862 to Torii et al., discloses the use of fluorine containing compounds with a quaternary ammonium salt, a water soluble or miscible organic solvent, an inorganic or organic acid and a surfactant.
U.S. Pat. No. 6,044,851 to Grieger et al., discloses the use of fluorine containing compounds with a quaternary ammonium fluoride, a water soluble or miscible organic solvent and a surfactant.
Moreover, heretofore, available cleaning compositions have required unduly long residence times or repeated applications in order to remove certain residues.
A suitable aqueous cleaning composition has been discovered that eliminates or substantially reduces the disadvantages or drawbacks of corrosion or substrate attack, particularly of copper, found with prior art cleaning components.
In view of the fact that prior art compositions have many short comings, the cleaning compositions according to the present invention are water miscible and biodegradable. Cleaning compositions according to the present invention are substantially non-flammable, non-corrosive, evidence relatively little (if any) tendency to evaporate, and are generally unreactive.
Compositions according to the invention not only remove residue, but have a high degree of efficacy, particularly at lower temperatures than is generally required with prior cleaning compositions.
Compositions according to the invention exhibit substantially no corrosive effects on the substrate, especially those containing copper, dielectrics or silicon.
Furthermore cleaning compositions according to the invention are devoid of undesirable chlorinated or phenolic components such as gallic acid, pyrogallol, and catechol or do not require the use of hot highly caustic components would be welcome by a semiconductor manufacturer, especially if the cleaning compositions and use thereof are not considered undesirable by regulatory agencies overseeing their production and use.
Most compositions according to the invention provide complete removal of residue, where such results are not always obtainable with the individual components for the removal of sidewall organometallic and metal oxide residues without any substantial corrosion of a copper substrate. Compositions according to the invention have a component of the composition or process that overcomes the aging problems associated with the phenolic type inhibitors.
Therefore in one aspect the present invention is a cleaning composition comprising from about 4 to 14% by weight monoethanolamine, from about 2 to 6.0% by weight Tetralkylammonium hydroxide, from about 0.3 to 3.5% by weight fluoride ion, a corrosion inhibitor being an effective amount of ascorbic acid; balance deionized water.
In another aspect the present invention is a method of cleaning a semiconductor device having an organic, metal organic polymer, inorganic salt, oxide, hydroxide, and/or complexes or combinations thereof as a film or residue comprising the steps of; contacting the semiconductor device with a cleaning composition containing from 4 to 14% by weight monoethanolamine, about 0.2 to 6.0% by weight tetralkylammonium hydroxide, about 0.3 to 3.5% by weight fluoride ion, an effective amount of ascorbic acid corrosion inhibitor, balance water at a temperature of between 25xc2x0 C. and 50xc2x0 C. for a period of time between 5 minutes and 60 minutes, rinsing the semiconductor device in deionized water, and drying the semiconductor device.